I want to invest money in the stock market, but I only want to start with $200. What website will let me?

Hi Alra,
I am assuming that you are here in the USA. If so I would highly recommend DRIPS, Dividend Reinvestment Plans (DRPs), if only because of the small amount of cash you have available, you cannot afford to be paying ANY commissions, they will eat through your $200 like a hot knife through butter at room temperature. With DRPS you are buying the stocks directly from the company itself without paying those commissions. I would also suggest that you add a set amount of dollars every month to your holdings. Only pick stocks that you have checked out and believe in, especially those that make products you buy and use and like. Look at this for the long term, gradually your account should increase in value. Then you are able to take some of those profits and trade riskier stocks through a regular trading account.
Good luck and don't forget to watch Jim Cramer's Mad Money on CNBC BOOYA

There are derivative instruments that you can use to gear yourself for a higher exposure. Altough on the flip side these instruments introduce greater risks.

Have a look at CFDs, Warrants, Options...

Trading Stocks (Shares)
http://www.mysharetrading.com/ Report It

try sharebuilder
they let you start out with as little as 4 dollars

montley fool

You should not invest in the stock market if you only have $200.00
I suggest you to save $2,000.00 and then open an account at ameritrade.com and then contact me if you need help.